A plasma display panel has a substrate on which electrodes are fabricated by performing industry known, photolithographic process steps. First, a photo resist covers a layer of electrode material on the substrate. The, according to a development process, photolithographic patterning is performed by directing a beam of electromagnetic radiation through a patterned photolithographic mask. The beam is patterned by the mask, and is focused to irradiate a photo resist layer with an un-irradiated pattern. Then, the patterned photo resist layer is washed with a developer to remove the non-irradiated part, which leaves behind a patterned photo resist. The patterned photo resist covers a layer of electrode material on the substrate.
With the patterned photo resist in place, selective etching is performed to etch the electrode material, which forms a pattern of electrodes on the substrate of the plasma display panel. The electrodes have elongated bus line conductors that interconnect with spaced apart contact pads.
Then the substrate and the pattern of electrodes are fired, at elevated temperatures to drive off organic compounds, to unify electrode particles into a solid mass, and to increase the conductivity, durability and permanence of the electrodes under voltage stress, as well as, to secure the electrodes on the substrate.
FIG. 4 discloses an exemplary pattern of electrodes having bus line conductors connected to pads. The bus line conductors have narrow widths, or narrow width dimensions. The pads have wide widths, or wide width dimensions, because the pads need relatively large surface areas to establish electrical connections with corresponding, hexagonal shaped pixel electrodes. As disclosed by FIG. 4, the pixel electrodes cover and engage corresponding pads.
FIG. 5 discloses a break in the electrode pattern. The break appears during the process of developing the electrode pattern, or during the process of firing the electrode pattern.
The break is caused by development of a patterned electrode with an abrupt change in the width of an electrode where a corresponding, narrow bus line conductor intersects a wide pad. When the patterned mask is developed, a fluent developer flows lengthwise of the electrodes. Because the electrodes lack a streamlined profile, the fluent developer erodes side cuts laterally into the patterned mask. The side cuts in the patterned mask are transferred to the electrodes, which make electrodes that are weakened by patterned side cuts, and susceptible to a break. During a firing process at a temperature elevated above ambient, a break in an electrode is due to a wide width of the pad that shrinks more, while cooling, than does the narrow width of an intersecting bus line conductor.